Recording of electrical impulses



Dec. 21, 1937. K R 2,@2,753

RECORDING OF ELECTRICAL IMPULSES Filed July 23, 1956 Patented Dec. 21, 1937 UNITED STATES PATENT OFFICE Karl Sehwarz, Berlin,

Germany, assignor to Klangfilm G. m. b. H., Berlin, Germany, a corporation of Germany Application July 23, 1936, Serial No. 92,085 In Germany October 30, 1935 5 Claims.

This invention relates to the recording of electrical impulses, such as those of audio frequency and has for its principal object the provision of an improved impulse recorder which is operable to 5 produce a combined record of the impulses and of a current varying as the envelope of the impulses. It pertains more particularly to the recorder elements which function to produce the envelope component of the record and is efiective in minimizing the background noise otherwise incident to the reproduction of photographic sound records and the like.

Accordingly a further object of the invention is the provision of an improved recorder assembly which functions to shade the otherwise clear portion of a photographic sound record positive in a manner to maintain the noise to signal ratio at a value consistent with the satisfactory reproduction of the recorded sound.

20 The invention will be better understood from the following description when considered in connection with the accompanying drawing and its scope will be apparent from the appended claims.

Referring to the drawing:

25 Fig. 1 illustrates a light shutter operating mechanism of the rotating coil type, and

Figs. 2 and 3 illustrate a similar mechanism of the plunger coil type.

In Fig. 1, item l designates a permanent mag- 30 net with pole shoes I I, of half circular shape. Between the pole shoes there moves the rotating coil system l3 against the force of a spring l2. The control currents are applied to the rotating coil across terminals l4 and IS. The shaft I6 35 of the rotating coil I3, has the diaphragm or light shutter I! connected therewith, whose maximum deviations are fixedly established by the stop members l8, l9 which have a damping action.

Since the rotating coil system is permitted to oscillate only in the direction of the arrow, the

diaphragm ll must be shaped as indicated in Fig.

1 so that a uniform covering on both sides of the slot 20 will be obtained per unit of deviation of the rotating coil system.

Figs. 2 and 3 illustrate a plunger coil system in which item I is the magnet system, 2 is the plunger coil which can move in the direction of the arrow under the influence of the currents passing through the coil 2, and the constant field of magnet I. The magnet is so constructed that at the plates 3 and 4 an N-pole is produced and at the place 5 it is an S-pole. The plunger coil has the diaphragm or shutter I1 connected thereto across an arm 6. The diaphragm I1 is held in its resting position by the springs I and 8. These springs are screwed to pins 9. The maximum deviations of the system are determined by the stop members l8, l9 having a damping action.

It will of course be understood that the illumination of the slit 20 is modulated in accordance with the impulses to be recorded and that the sloped edges of the diaphragm or shutter I! follow the general contour or envelope of the recorded impulse peaks.

I claim as my invention:

1. The combination of a light slit adapted to have its illumination modulated in accordance with the impulses to be recorded, means for producing a magnetic field, a shutter provided with a V-shaped edge traversing said slit, and a coil movably mounted in said field and connected to said shutter for causing said edge to follow the envelope of said illumination.

2. The combination of a light slit adapted to have its illumination modulated in accordance with the impulses to be recorded, means for producing a magnetic field, a shutter provided with a V-shaped edge traversing said slit, and. a coil rotatably movably mounted in said field and connected to said shutter for causing said edge to follow the envelope of said illumination.

3. The combination of a light slit adapted to have its illumination modulated in accordance with the impulses to be recorded, means for producing a magnetic field, a shutter provided with a V-shaped edge traversing said slit, and a plunger type coil movably mounted in said field and connected to said shutter for causing said edge to follow the envelope of said illumination.

4. The combination of a light slit adapted to have its illumination modulated in accordance with the impulses to be recorded, means for producing a magnetic field, a shutter provided with a V-shaped edge traversing said slit, a coil movably mounted in said field and connected to said shutter for causing said edge to follow the envelope of said illumination, and means for damping the motion of said shutter.

5. The combination of a light slit adapted to have its illumination modulated in accordance with the impulses to be recorded, means for producing a magnetic field, a shutter provided with a V-shaped edge traversing said slit, a coil movably mounted in said field and connected to said shutter for causing said edge to follow the envelope of said illumination, and resilient means for predetermining the zero position of said shutter.

KARL SCHWARZ. 

